Sex differences widen as society becomes more equitable

From Gender equity can cause sex differences to grow bigger by Rob Brooks.

How do sex differences arise? Few questions animate as much disagreement and contention, in everyday society and in academic study. For as long as the question has been asked, the answers have fallen between two extremes: sex differences arise innately, or they come from social experience.

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The evidence is in: samples of women and men differ, on average, in a vast number of personality, emotional, behavioural, cognitive and attitudinal measures. Yes, the sexes overlap. And one cannot and should not rush to inferring anything about a person from the average properties of those who share the same genital configuration. But sex differences are present, found in many replicate studies, and often similar in magnitude across societies.

Rationalist biology holds that such differences have evolved. The combination of traits that made our male ancestors successful fathers differ from those that turned our female ancestors into successful mothers. This idea chimes with the repeated presence of so many sex differences across cultures, but the fact that the magnitude of the differences varies considerably among cultures suggests much more than biological determinism.

The Empiricist thinking that has dominated the study of gender in the social sciences for more than half a century holds that sex differences arise from extensive socialisation, and differences in the power that women and men hold and wield. This view brings us the notion that by ceasing to socialise boys and girls into stereotyped sex roles, and breaking down power inequities within societies, sex differences will diminish.

The idea that teaching, socialisation and structural change will progressively erode sex differences and gendered behaviour has a powerful hold. It underpins social interventions from "No Gender December" (a.k.a. the Christmastime war on pink toys) to the current Stop it at the Start campaign against domestic violence.

A recent book chapter by eminent evolutionary psychologist David P. Schmitt adds an interesting dimension, sure to be controversial, but also with considerable potential to rejuvenate debate. The book, The Evolution of Sexuality (Springer, editors Todd K Shackleford and Ranald D. Hansen), at US $139 will likely prove inaccesible to readers without access to an academic library.

Alice Eagly, Wendy Wood and Mary Johannesen-Schmidt, among the most persuasive advocates for the primacy of socialisation into sex roles, predicted that increasing gender equality would lead to "the demise of many sex differences". That prediction seems so intuitive, so consistent with contemporary thinking about gender equity, that it hardly needs testing. But Schmitt didn't think so. He recognised that not only should the idea be put to the test, but that there exists a wealth of data on cross-cultural on variation in personality, behavioural and other traits that could be matched with good measures of gender equity and sex role ideology.

Counter to the prediction of social role theory, in only 2 out of 28 traits examined by Schmitt did sex differences narrow as gender equity increased. In six traits, the sex difference remained stable, and in 20 traits it widened.

Not conclusive by any means, but food for thought.